This invention relates generally to furnaces for the burning of used oil and, more particularly, to the construction of the furnace to direct the flow of the exhaust gasses generated from the combustion of fuel within the furnace to enhance the efficiency of the operation of the furnace to heat an ambient medium such as ventilation air.
Multi oil furnaces are similar to standard oil burning furnaces, but have been adapted to handle oil products that have been previously used in a traditional lubricating operation, such as used crankcase oil up to 50 SAE, used transmission fluid, and even #2, #4 and #5 fuel oils. Such oil products can have significantly varying viscosities and significantly varying burning characteristics, as well. Typically, used oil products are collected into a tank to be supplied to the furnace from a single source. As furnaces are normally operated when the ambient air temperatures are sufficiently cold to warrant the use of the furnace, the supply of used oil to the furnace is normally as cold as the ambient temperature, which requires a preheating of the used oil to more efficiently effect a burning of the used oil products.
The burner nozzle combines a flow of compressed air with the flow of preheated used oil to atomize the used oil and inject a stream of compressed air and atomized used oil droplets into the burner chamber of the multi oil furnace where it is ignited to create a flame and provide a heat source. Known multi oil furnace burner nozzles utilize an in-line burner nozzle configuration coupled directly to the front door of the multi oil furnace.
The construction of the furnace is important in the efficiency of its operation. A burner chamber with a flame target at the end opposite the burner nozzle is provided to contain the flame and provide an exit for the combustion gases (or flue gases) past the target. Known furnace configurations, such as the Clean Burn Model CB-90 multi oil furnaces, redirect the combustion gases through a serpentine path to the side of the burner chamber utilizing conduits before discharging the gases from the furnace so that ventilation air can be forced around the conduits to absorb heat therefrom.